LT1 (93+) Ignitions

Roger Heflin rah at horizon.hit.net
Wed Feb 10 20:17:00 GMT 1999



I don't know what signals the computer wants.  Electromotive has a
computer/circuit that fakes the proper signals from a crank trigger to
make the computer happy.  I believe the opti-eliminator as it is
called cost about $300 or so.  With both the coils, crank trigger, and
faker the entire setup is $799.  The opti-eliminator has 3 wires (or
wire bundles) going out of it.  One goes to the crank trigger, one
goes to the coil pack controls, and one goes back to the stock opti
computuer.   I would guess since the signals are going straight into
the computer (I believe they are) that the signals are standard 5-v
cmos like voltage levels.   There may be some stuff in the opti to
actually clean up the signals before sending them.   

I believe both the low res and high res signals are basically crank
trigger signals, each optical wheel has a different number of teeth.
Someone on the f-body group (Mike Chaney, The one with the in car
dyno software) has a disection of the optispark on his web page, you
may be able to tell something about it from that.  You may also want
to ask him, since he has had one completely disassembled.  

If you want I can look in my service manual and see exactly what it
says, I believe it gives some details on the signals that can be
checked, and also I can look at the computer code running that sort of
stuff.  The service manual tends to give some pretty detailed info on
some things.

				Roger

On Wed, 10 Feb 1999, Bruce Plecan wrote:

> Anybody got any clues, or knowlege about what kind of signals
> (Pattern+Voltage) one might expect to see on Distrib low reference,
> Distributor ignition feed, Hi Resolution signal, low resolution signal,
> Ignition control?....
>   This is for the front mounted distributor.
> TIA
> Bruce
> 
> 




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